Issue #1214 by zAlexliu-8895 on OpenSees GitHub demonstrated a memory leak with creating patches for fiber sections. The script posted with the GitHub issue is reproduced below. import openseespy.opensees as ops Counter = 0 while Counter < 100000000: Counter += 1 ops.wipe() ops.model('basic', '-ndm', 2, '-ndf', 3) ops.uniaxialMaterial("Concrete02", 1, -33, -0.0015, -20, -0.005, 0.1, 2.2, … Continue reading Runnin’ Down a Leak
Author: Michael H. Scott
Minimal Creep and Shrinkage Example
In class, I tend to avoid talking about creep and shrinkage of concrete. I say "compression steel is good because long term deflections due to creep are bad", then move on to seemingly more interesting topics like how to find the neutral axis, bypassing shrinkage altogether. However, creep and shrinkage remain large mysteries to most … Continue reading Minimal Creep and Shrinkage Example
How to Keep Your OpenSees Code Private on GitHub
I often mention the Concrete23 material model, but you won't find it in the main OpenSees GitHub repository or in any of the repo's public forks. You won't find Concrete23 because it doesn't exist. Or maybe the model does exist but I keep it in a private fork of OpenSees. You'll never know... Let's assume … Continue reading How to Keep Your OpenSees Code Private on GitHub
Abstract Frenzy
The deadline to submit abstracts for the 18th World Conference on Earthquake Engineering (18WCEE), the quadrennial venue to share earthquake engineering ideas and research, is right around the corner. Noting that 93% of statistics are made up, WCEE abstracts have an 80% acceptance rate; however, some of the ensuing papers are impactful. And in many … Continue reading Abstract Frenzy
Arc Length Parameters
Beyond load control, which cannot get past peaks in load-displacement response, OpenSees has several "continuation" methods for nonlinear static analysis of structural models. Implementation of continuation methods is based on the incremental-iterative framework by Clarke and Hancock (1990) with displacement control, minimum unbalanced displacement norm (MUDN), and arc length among the most frequently used in … Continue reading Arc Length Parameters
Run OpenSees in the Cloud
Many OpenSees use cases, from the embarrassingly parallel to large, high fidelity models, require high performance computing (HPC). But even today, HPC remains out of reach for many OpenSees users for a variety of reasons. If you or your organization is able to purchase HPC hardware, the overhead to maintain and operate the hardware remains … Continue reading Run OpenSees in the Cloud
A Rigid Bar Walks Into a Bar
OpenSees has two rigidLink commands that enforce constraints between a primary node (pNode) and a secondary node (sNode). ops.rigidLink('-beam',pNode,sNode) ops.rigidLink('-bar',pNode,sNode) The beam option works well, enforcing linear kinematic constraints as if the two nodes were connected by a beam of infinite axial and flexural stiffness. The bar option should give constraints assuming only infinite axial … Continue reading A Rigid Bar Walks Into a Bar
My Favorite Ternary Operation
Most native C++ operations are binary, taking two arguments, e.g., a + b, or unary, taking one argument, e.g., a++. But C++ (and many other languages) has a native "conditional operator", which is ternary, taking three arguments. Known simply as ?:, the conditional operator has the following syntax (condition) ? true_outcome : false_outcome; The conditional … Continue reading My Favorite Ternary Operation
How to Bend Beams in 3D
Most structural frame models are analyzed in two dimensions (2D), for a variety of legitimate reasons. But sometimes, you have to go to three dimensions (3D). And the most confusing thing about making that jump in OpenSees is the geometric transformation and its "vector in the x-z plane". Instead of going into the details of … Continue reading How to Bend Beams in 3D
Pity the Reader
Kurt Vonnegut was a 20th century American author, best known for Slaughterhouse-Five. Although Vonnegut passed away in 2007, one of his former writing students, Suzanne McConnell, published in 2019 Pity the Reader: On Writing with Style, a collection of Vonnegut's writing advice. You will find the ground work for a chapter or two of Pity … Continue reading Pity the Reader